Many semiconductor devices typically require at least two levels of interconnects that typically contain aluminum or an aluminum-containing alloy. During the formation of a via opening, which is a contact opening that is formed between two interconnect levels, a veil material can be formed along the sides of the via opening. More specifically, during the via etch, the oxide or other insulating layer is etched until the aluminum-containing material within the lower interconnect is exposed. This process forms a veil material that typically includes aluminum, the insulating material, and compounds from the photoresist. Removing this veil material has proven to be extremely difficult as the veil needs to be removed without excessively etching the insulating layer or causing adverse reactions with the underlying aluminum-containing layer.
An attempt to address the prior art problem has been to use fluorine and water vapor during ash processing to try to remove the veil. This process does not effectively remove the veil reproduceably for a manufacturing environment. Wet chemical processing has also been used, however, the presence of fluorine-containing solvents are likely to attack the insulating layer too much and any chemicals used to remove aluminum within the veil would attack the aluminum within the interconnect. Use of organic solvents has been commonly used within the semiconductor industry. However, the use of solvents by themselves has proved insufficient as heavily veiled via openings are not adequately cleaned using an organic solvent clean alone.